The Prevalence of Renal Impairment in Patients with Spondyloarthritis: Results from the International ASAS-COMOSPA Study.

OBJECTIVE: To assess the prevalence and association of renal dysfunction in patients with spondyloarthritis (SpA).

METHODS: The ASAS-COMOSPA (Assessment of Spondyloarthritis international Society-COMOrbidities in SPondyloArthritis) was an international study (22 participating countries from 4 continents) investigating comorbidities in SpA. Renal function was assessed based on estimated glomerular filtration rate (eGFR) calculated using the Modification of Diet in Renal Disease equation. SpA characteristics and risk factors for renal impairment were collected. Nonsteroidal antiinflammatory drug (NSAID) use was assessed based on current intake (last 3 mos).

RESULTS: Of the 3984 patients recruited, 2098 (52.6%) were analyzed after excluding outliers and patients with no available eGFR measurement [male sex: 63.5%; age: 45.3 yrs; disease duration: 8.6 years; HLA-B27+: 73.1%; Bath Ankylosing Spondylitis Activity Index (BASDAI): 3.6/10]. Overall, 153 patients (5.2%, mean age: 53.6 yrs) exhibited an eGFR < 60 ml/min/1.73 m2 . In univariate analysis, renal impairment was associated with age (p < 0.001), HLA-B27 positivity (p = 0.003), several cardiovascular (CV) risk factors (history of hypertension, p < 0.001; systolic blood pressure, p = 0.009; diabetes, p = 0.005; and Framingham risk score, p < 0.001), disease activity scores [BASDAI, p = 0.001; Ankylosing Spondylitis Disease Activity Score-C-reactive protein (ASDAS-CRP), p < 0.001], functional variables (Bath Ankylosing Spondylitis Functional Index, p < 0.001), inflammatory biomarkers (erythrocyte and CRP, both p < 0.001), and NSAID intake since onset of disease (percentage of days, p = 0.008). However, there was no association with disease duration, disease severity, or ASAS-NSAID score. In multivariate analysis, age (45-59 yrs: OR 1.9, > 60 yrs: OR 6.2), HLA-B27 positivity (OR 0.51), and CRP (OR 1.3) remained significantly associated with eGFR < 60 ml/min/1.73 m2 .

CONCLUSION: Renal impairment was associated with age, HLA-B27 positivity, and inflammation, though not with CV risk factors, disease severity, or NSAID intake in patients with SpA.